One of the major drawbacks existing in furnaces and boilers is the basic problem of the combustion process, which requires a lot of air in all the parts of the combustion chamber to ensure complete combustion. Insufficient air results in incomplete combustion and the production of unburnt carbon which appears as black smoke. However, the use of excess air is likely to cause inefficient operation by chilling the flame and removing heat unnecessarily as sensible heat in the surplus air. In such circumstances the exhaust gases contain both free carbon and combustible gases and results in the potential waste of heat and energy.
Secondly, the exhaust gases result in the formation of a layer on the top of the furnace or boiler.
Those skilled in the art of pollution control are familiar with many catalysts developed for the direct reduction of nitrogen in fuel gas streams. Several such catalysts are available commercially. A common feature of such catalysts is for the reduction of nitrogen oxides.
In the production of alloys metal is added first and subsequently after the metal melts other metals and chemicals are added to form the resultant product. During the melting period, pure oxygen is lanced inside the furnace through electrical resistance welded pipes with considerable pressure to quicken the process of melting.
For such operations, liquid oxygen in a considerable quantity with reference to the capacity of the furnaces is to be stored.
In the existing furnaces, the operation of the lancing of oxygen is purely manual since the welded pipes are introduced manually inside the furnaces up to the melting point of the metals which are already fed in the furnaces. Hence, it is impossible for humans beings to be nearer to the hot furnace due to the high temperature and unbearable heat and light. The lancing operation is always intermittent and not continuous which is required for quicker composition of the alloy at the melting time. Due to this, the melting time increases and due to the intermittent operation which is not continuous, the resultant alloy does not get the required technical specification of the correctly mixed alloy compound.
In the case of the steel and petrochemical industries, molecular nitrogen from the atmosphere dissociates into its atomic form and is readily absorbed into the heated steel reducing its formability. This makes it unusable for applications requiring a high degree of ductility. To produce steel that can be deeply pressed over dies, the nitrogen level must be reduced to about 30-50 PPM.
It has been found that in the conventional steel making processes the largest amount of nitrogen is absorbed by steel during initial melting and that nitrogen levels are reduced when oxygen is injected into liquid steel to react into carbon. Specifically carbon monoxide formed during this reaction tends to flush out the nitrogen. The presence of foamy slag covering the molten metal reduces the chances for more nitrogen to be absorbed. This foam is produced when carbon dioxide gases from the steel bath form small bubbles within the slab; it has the consistency approximately of the foam that forms on the top of a carbonated beverage.
The biggest problem faced by the present industries is the problem of high energy cost and metallurgical loss. Another major problem is pollution.
Similarly, liquified petroleum gas (LPG) is a common and essential domestic commodity and is used in many homes.
It has been found that the combustion of fuel gases (commercial/domestic) is found to be more easily controllable than that of solid fuel because the mixing of fuel and the combustion air can be controlled more perfectly. The ease of achieving complete combustion with the little excess air is somewhat less with fuel gases consisting predominantly of hydrocarbons in the case of LPG than it is with gas mixtures containing substantial proportions of hydrogen and carbon monoxide.
The mixture of combustible gas cannot be ignited, nor can it be burn if the proportion of combustible gas which it contains is either very small or unduly large. However, it does not mean that the gases cannot be oxidized by heating the mixture.
The LPG which is used domestically in cylinders is under relatively low pressure. The largest part of the LPG produced is used in central heating systems and the next largest as raw material for chemical plants.